Abstract: An apparatus for performing Raman spectral analysis of a sample is described, comprising a coherent light source, an first optical chain to direct the coherent light to impinge on the sample, a second optical chain to direct the scattered light onto a diffraction grating, and a third optical chain to direct the diffracted light onto detection array. The diffraction grating is a stairstep with a metalized surface, and a plurality of metalized stripes on a flat surface is disposed in a direction orthogonal to the long dimension of the stairsteps. The region between the flat surface and the stairstep is transparent. The zeroth-order fringe is selected by a slit and directed onto camera. The resultant interferogram is Fourier transformed to produce a representation of the Raman spectrum.

Abstract: An apparatus for performing Raman spectral analysis of a sample is described, comprising a coherent light source, an first optical chain to direct the coherent light to impinge on the sample, a second optical chain to direct the scattered light onto a diffraction grating, and a third optical chain to direct the diffracted light onto detection array. The diffraction grating is a plurality of alternating-slope stairsteps, wherein the portion of the step disposed parallel to the base of the diffraction grating is disposed so as to be orthogonal to the path of the scattered light from the second optical chain. The zeroth-order fringe is selected by a slit and directed onto camera. The resultant interferogram is Fourier transformed to produce a representation of the Raman spectrum.

Abstract: An apparatus for performing Raman spectral analysis of a sample is described, comprising a coherent light source, an first optical chain to direct the coherent light to impinge on the sample, a second optical chain to direct the scattered light onto a diffraction grating, and a third optical chain to direct the diffracted light onto detection array. The diffraction grating is a stairstep with a metalized surface, and a plurality of metalized stripes on a flat surface is disposed in a direction orthogonal to the long dimension of the stairsteps. The region between the flat surface and the stairstep is transparent. The zeroth-order fringe is selected by a slit and directed onto camera. The resultant interferogram is Fourier transformed to produce a representation of the Raman spectrum.

Abstract: An apparatus for performing Raman spectral analysis of a sample is described, comprising a coherent light source, an first optical chain to direct the coherent light to impinge on the sample, a second optical chain to direct the scattered light onto a diffraction grating, and a third optical chain to direct the diffracted light onto detection array. The diffraction grating is a plurality of alternating-slope stairsteps, wherein the portion of the step disposed parallel to the base of the diffraction grating is disposed so as to be orthogonal to the path of the scattered light from the second optical chain. The zeroth-order fringe is selected by a slit and directed onto camera. The resultant interferogram is Fourier transformed to produce a representation of the Raman spectrum.

Abstract: A chemical vapor sensor is provided that passively measures a chemical species of interest with high sensitivity and chemical specificity. In an aspect, ethanol vapor in a vehicle cabin is measured, and sufficient sensitivity is provided to passively detect a motor vehicle driver that exceeds a legal limit of blood alcohol concentration (BAC), for use with vehicle safety systems. The sensor can be situated in an inconspicuous vehicle cabin location and operate independently without requiring active involvement by a driver. A vapor concentrator is utilized to amplify a sampled vapor concentration to a detectible level for use with an infrared (IR) detector. In an aspect, in comparison to conventional chemical sensors, the sensitivity of detection of ethanol vapor is increased by a factor of about 1,000. Further, a single channel of infrared detection is utilized avoiding spurious infrared absorption and making the chemical vapor sensor less costly to implement.

Abstract: System and methods for determining a concentration of urea in an aqueous solution disposed in a container are provided. The system includes an infrared light source and an infrared light detector. The system further includes a window disposed proximate to an aperture of the container, such that the infrared light at a first light intensity level from the infrared light source passes through a first portion of the window toward the aqueous solution. A portion of the infrared light is absorbed by the aqueous solution, and a second portion of the infrared light is reflected from the aqueous solution and through a second portion of the window. The infrared light detector system generates a first signal indicative of a second light intensity level based on the second portion of infrared light. The system further includes a microprocessor that determines the second light intensity level based on the first signal, and further determines a urea concentration based on the first and second light intensity levels.

Abstract: In one embodiment, a sensor assembly has a sensor housing forming a fluid chamber and a magnetostrictive wire that undergoes stress induced by fluid in the chamber. The wire defines opposed ends, each being associated with a respective terminal. Respective hermetic seals penetrate the housing and are coupled to the respective terminals.

Abstract: In one embodiment, a sensor assembly has a magnetostrictive (MS) element and a sensor housing defining at least one active wall. A sensor channel is disposed on a first side of the active wall, with the MS element being disposed in the sensor channel and closely received therein. A fluid is on a second side of the active wall, and the active wall is the wall through which stress from pressure of the fluid causes stress on the MS element. The sensor channel defines an axis parallel to the active wall, and the MS element is positioned adjacent the active wall by sliding the MS element into an end of the sensor channel in a direction parallel to the active wall.

Abstract: In one embodiment a sensor assembly has a magnetostrictive (MR) element in a sensor housing. The MR element has a sensing part engaged with a wire coil and a frusto-conical sealing part juxtaposed with a fluid the pressure of which is to be sensed.

Abstract: In one embodiment, a sensor assembly has a sensor housing forming a fluid chamber having a surface defining a normal axis. A magnetostrictive (MS) core that defines a central longitudinal axis is subjected to stress induced by pressurized fluid in the chamber. An excitation coil is coupled to the core to induce a magnetic flux therein. The central longitudinal axis of the core is coaxial with the axis normal to the fluid chamber surface.

Abstract: A thermoelectric material having enhanced Seebeck coefficient is characterized by a microstructure comprising nanoscale Pb inclusions dispersed in matrix substantially composed of PbTe. The excess Pb is obtained either by adding Pb in an amount greater than the stoichiometric amount needed to form PbTe, or by adding an additive effective to getter Te so as to produce the desired excess. The method is generally applicable to enhance thermoelectric properties of compounds of Pb, Sn or Ge, and Te, Se, or S.

Abstract: A brake system including a brake pad shaped and located to apply pressure to a brake rotor and an actuator shaped and located to apply pressure to the brake pad to cause the brake pad to apply pressure to the rotor. The system further includes a sensor material which varies in resistance when the actuator applies pressure to the brake pad, wherein the sensor material include an electrically insulating material with electrically conductive particles distributed therein. The system further includes a controller operatively coupled to the sensor material to detect a change in resistance of the sensor material.

Abstract: A thermoelectric nanogranular material with an enhanced Seebeck coefficient is provided. The thermoelectric nanogranular material includes particles having a grain size d. The grain size d is characterized by the relationship mfp/2<d<5mfp, where mfp is the phonon-limited mean free path of an equivalent bulk thermoelectric material prior to processing the bulk thermoelectric material into the thermoelectric nanogranular material having a grain size d. A method of making a thermoelectric nanogranular material is also provided. The method includes preparing a bulk thermoelectric material, reducing the bulk thermoelectric material into a powder, and filtering the powder to retain only those particles having a grain size d. The method also includes pressing the retained particles at a predetermined pressure and sintering the pressed particles at a predetermined temperature for a predetermined period of time in a predetermined atmosphere.

Abstract: A semiconductor film is provided characterized by having high carrier mobility and carrier density. The semiconductor film is doped with the rare-earth element erbium so as to improve its temperature stability. The semiconductor film is thereby particularly suited for use as a magnetic field sensing device, such as a Hall effect sensor or magnetoresistor. The semiconductor film is formed from a narrow-gap Group III-V compound, preferably indium antimonide, which is n-doped with the erbium to provide an electron density sufficient to increase temperature stability. In particular, the semiconductor film is characterized by a nini-structure which is generated using a slab-doping technique. The slab-doping process encompasses the growing of alternating layers of doped and undoped layers of the Group III-V compound, with the doped layers being substantially thinner than the undoped layers, and preferably as thin as one atomic plane.

Abstract: For increased sensitivity, an improved position sensor includes a magnetic circuit in which the stationary portion includes a permanent magnet whose width is optimally 1.5 times the tooth pitch of the exciter portion of the sensor and the magnet face proximate the exciter includes a thin layer of ferromagnetic material over which is centered a narrow magnetic sensing element, such as a magnetoresistor. The sensing element has a width typically less than the tooth width. The sensing element includes a thin film of a monocrystalline semiconductive material, preferably having only a moderate bulk mobility and a larger band gap, such as indium arsenide. Current carriers flow along the length of the thin film in a surface accumulation layer, effective to provide a significant apparent increase in mobility and conductivity of said semiconductive material, and an actual increase in magnetic sensitivity and temperature insensitivity.